Elements

1. Aim: To understand that all substances are made of tiny particles and learn about elements and molecules.

2. Requirements: teapot with a lid, water, heat source (stove or burner), and spray pump filled with water.

3. Procedure

• Boiling Water in Teapot: Pour water into the teapot and cover it with the lid. Heat the teapot until the water starts to boil. Observe the inside of the lid; you will notice water droplets.
• Using a Spray Pump: Fill the spray pump with water and spray it into the air. Observe how the water breaks into tiny droplets.

4. Conclusion

• The water droplets on the lid of the teapot form due to the condensation of vapour. The vapour is made of tiny particles that are too small to see.
• The spray forms small water droplets, showing that water can be broken into tiny particles.
• All substances are made of molecules, which are extremely small particles.
• If a molecule is made up of identical atoms, the substance is called an element (e.g., oxygen or hydrogen).

Spray-pump

An element is a substance whose molecules are made of identical atoms. For example, oxygen, copper, and hydrogen. Elements can be normally divided into metals, non-metals and metalloids. Elements exist in solid, liquid, or gaseous states. The smallest particles of an element are called atoms. Atoms are too small to see with the naked eye, but when many atoms come together, they become visible. Molecules are made up of two or more atoms bonded together. For example, an oxygen molecule (O₂) has two oxygen atoms.

Contribution of Great Scientists:

• Antoine Laurent Lavoisier (1743–94), a French chemist, defined an element as a basic form of matter that cannot be broken down into simpler substances by chemical reactions.
• Democritus named the small particles of elements ‘atom’ because in the Greek language, atomos means indivisible.
• In 1803, John Dalton proposed his theory, stating that atoms cannot be created or divided into smaller particles or destroyed. He used certain symbols to represent elements.
  For example : © Copper, ⊕ Sulphur, ⊖ Hydrogen.